Effect of cochlear implant electrode insertion on middle-ear function as measured by intra-operative laser Doppler vibrometry

Hypothesis: The aim of this study was to investigate the impact of cochlear implant electrode insertion on middle-ear low frequency function in humans.Background: Preservation of residual low frequency hearing with addition of electrical speech processing can improve the speech perception abilities and hearing in noise of cochlear implant users. Preservation of low frequency hearing requires an intact middle-ear conductive mechanism in addition to intact inner-ear mechanisms. Little is known about the effect of a cochlear implant electrode on middle-ear function.Methods: Stapes displacement was measured in seven patients undergoing cochlear implantation. Measurements were carried out intra-operatively before and after electrode insertion. Each patient acted as his or her own control. Sound was delivered into the external auditory canal via a speaker and calibrated via a probe microphone. The speaker and probe microphone were integrated into an individually custom-made ear mould. Ossicular displacement in response to a multisine stimulus at 80 dB SPL was measured at the incudostapedial joint via the posterior tympanotomy, using an operating microscope mounted laser Doppler vibrometry system.Results: Insertion of a cochlear implant electrode into the scala tympani had a variable effect on stapes displacement. In three patients, there was little change in stapes displacement following electrode insertion. In two patients, there was a significant increase, while in a further two there was a significant reduction in stapes displacement. This variability may reflect alteration of cochlear impedance, possibly due to differing loss of perilymph associated with the electrode insertion.Conclusion: Insertion of a cochlear implant electrode produces a change in stapes displacement at low frequencies, which may have an effect on residual low frequency hearing thresholds

Sustainable building solutions: a review of lessons from the natural world

The realisation that much of conventional. modern architecture is not sustainable over the long term is not new. Typical approaches are aimed at using energy and materials more efficiently. However, by clearly understanding the natural processes and their interactions with human needs in view, designers can create buildings that are delightful. functional productive and regenerative by design. The paper aims to review the biomimetics literature that is relevant to building materials and design. Biomimetics is the abstraction of good design from Nature, an enabling interdisciplinary science. particularly interested in emerging properties of materials and structures as a result of their hierarchical organisation. Biomimetics provides ideas relevant to: graded functionality of materials (nano-scale), adaptive response (nano-, micro-. and macro-scales): integrated intelligence (sensing and actuation at all scales), architecture and additional functionality. There are many examples in biology where emergent response of plants and animals to temperature, humidity and other changes in their physical environments is based on relatively simple physical principles. However, the implementation of design solutions which exploit these principles is where inspiration for man-made structures should be. We analyse specific examples of sustainability from Nature and the benefits or value that these solutions have brought to different creatures. By doing this, we appreciate how the natural world fits into the world of sustainable buildings and how as building engineers we can value its true application in delivering sustainable building

Compression dynamique du bois

Le comportement du bois en compression à grandes vitesses de déformation est relativement peu connu. La méthode des barres d’Hopkinson a été utilisée pour étudier la réponse mécanique du bois à des vitesses de déformation de l’ordre de 0.01 – 0.001 s-1, soit dans l’axe des fibres soit dans les directions normales à l’axe. Les courbes contrainte-déformation obtenues pour des bois différents (feuillus, résineux) sont comparées en fonction de leurs densités et structure cellulaire

TWIG: A model to simulate the gravitropic response of a tree axis in the frame of elasticity and viscoelasticity, at intra-annual time scale

International audienceTrees are able to maintain or to modify the orientation of their axes (trunks or branches) by tropic movements. For axes in which elongation is achieved but cambial growth active, the tropic movements are due to the production of a particular wood, called reaction wood which is prestressed within the growing tree. Several models have been developed to simulate the gravitropic response of axes in trees due to the formation of reaction wood, all within the frame of linear elasticity and considering the wood maturation as instantaneous. The effect viscoelasticity of wood has, to our knowledge, never been considered. The TWIG model presented in this paper aims at simulating the gravitropic movement of a tree axis at the intra-annual scale. In this work we studied both the effect of a non instantaneous maturation process and of viscoelasticity. For this purpose, we considered the elastic case with maturation considered as an instantaneous process as the reference. The introduction of viscoelasticity in TWIG has been done by coupling TWIG to a model developed for bridges. Indeed from a purely mechanical point of view, bridges and trees are very similar: they are structures which are built in stages, they are made of several materials (composite structures), their materials are prestressed (wood is prestressed during the maturation process as a result of polymerisation of lignin and cellulose to form the secondary cell wall and concrete is prestressed during drying). Simulations gave evidence that the reorientation process of axes can be significantly influenced by the kinetics of maturation. Moreover the model has now to be tested with more experimental data of wood viscoelasticity but it appears that in the range of a relaxation time from 0 to 50 days, viscoelasticity has an important effect on the evolution of tree shape as well as on the values of prestresses

The in-plane elastic properties of hierarchical composite cellular materials: Synergy of hierarchy, material heterogeneity and cell topologies at different levels

FO and EB are supported by the Queen Mary University of London Start-Up grant for new academics. NMP is supported by the European Research Council (ERC StG Ideas 2011 BIHSNAM n. 279985, ERC PoC 2015 SILKENE nr. 693670), by the European Commission under the Graphene Flagship (WP14 Polymer Nanocomposites, n. 696656)

Tooling design and microwave curing technologies for the manufacturing of fiber-reinforced polymer composites in aerospace applications

The increasing demand for high-performance and quality polymer composite materials has led to international research effort on pursuing advanced tooling design and new processing technologies to satisfy the highly specialized requirements of composite components used in the aerospace industry. This paper reports the problems in the fabrication of advanced composite materials identified through literature survey, and an investigation carried out by the authors about the composite manufacturing status in China’s aerospace industry. Current tooling design technologies use tooling materials which cannot match the thermal expansion coefficient of composite parts, and hardly consider the calibration of tooling surface. Current autoclave curing technologies cannot ensure high accuracy of large composite materials because of the wide range of temperature gradients and long curing cycles. It has been identified that microwave curing has the potential to solve those problems. The proposed technologies for the manufacturing of fiber-reinforced polymer composite materials include the design of tooling using anisotropy composite materials with characteristics for compensating part deformation during forming process, and vacuum-pressure microwave curing technology. Those technologies are mainly for ensuring the high accuracy of anisotropic composite parts in aerospace applications with large size (both in length and thickness) and complex shapes. Experiments have been carried out in this on-going research project and the results have been verified with engineering applications in one of the project collaborating companies